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I've recently bought a 1Gb Philips MP3 player, and I'm enjoying much of my music collection whilst enduring the services of London Underground on my journey to and from work.

This player has a "shuffle" feature, which in theory plays the tracks in a random order. I say in theory, because I've found that the player seems to favour certain albums, and sometimes goes into a sequential mode - as if the shuffle wasn't turned on. Taking the battery out seems to restore the shuffle. Anyway I decided I haven't got the time and the anal fixation to gather evidence for this bug and report it to Philips.

So, instead, I've used some Perl to scramble together a random selection of tracks from my whole collection - that which I have so far ripped to my hard drive. The code uses some statistics to try and pick tracks by their length, which should try and give a representative sample of track lengths (it uses the file size to do this). It's using my File::Wildcard to derive the file name in the destination directory. I use the tool below to make a number of selections as directories of symlinks (these can be manually tweaked to remove any tracks you don't like), then use cp -rL to copy to the USB player.

#!/usr/bin/perl use strict; use warnings; use File::Wildcard; use Getopt::Long; my $music; my $output; my $size = 134217728; # default 128M selection. GetOptions( 'source=s' => \$music, 'output=s' => \$output, 'size=i' => \$size, ); $music =~ s!/$!!; #! my $wc = File::Wildcard->new( path => "$music///", match => qr(/\d*\s*([^/]+\.(?:wma|mp3))$), derive => ["$output/\$1"], ); my @allsongs; my $sum=0; my $sumsq=0; while (my $found = $wc->next) { my ($song,$dest) = @$found; my $siz = (stat $song)[7]; $sum += $siz; $sumsq += $siz * $siz; push @allsongs,[$song,$siz,$dest]; } my $count = scalar @allsongs; my $mean = $sum / $count; my $sd = sqrt( $sumsq / $count - $mean * $mean); my $nsamp = int( $mean / $sd ); my @songs = sort {$a->[1] <=> $b->[1]} @allsongs; my %seen; while ($size > 20971520) { my $pt = 0; $pt += rand for (1..$nsamp); my $idx = int( $pt / $nsamp * $count); my ($song,$ssize,$dest) = @{$songs[$idx]}; next if exists $seen{$song}; $seen{$song}++; print $song,"\n"; symlink $song, $dest; $size -= $ssize; }

--

Oh Lord, won’t you burn me a Knoppix CD ?
My friends all rate Windows, I must disagree.
Your powers of persuasion will set them all free,
So oh Lord, won’t you burn me a Knoppix CD ?
(Missquoting Janis Joplin)


In reply to MP3 shuffler by rinceWind

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